PFAS-Contaminated Soil Site in Germany: Nontarget Screening before and after Direct TOP Assay by Kendrick Mass Defect...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Soil Science

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• Long-term groundwater contamination is a significant concern due to PFAS persistence.
• Previous studies identified some PFAS in surface and drinking water near the study site.

Purpose of the Study:

• To comprehensively characterize PFAS contamination in agricultural soil using nontarget screening (NTS).
• To identify novel PFAS and PFAS classes previously unknown in this soil.
• To assess the effectiveness of NTS compared to traditional methods for PFAS analysis.

Main Methods:

• Nontarget screening (NTS) using Kendrick mass defect and MS2 fragment mass differences (FindPFΔS).
• Analysis of a composite soil sample from contaminated agricultural land in northwestern Germany.
• Semi-quantification of PFAS using PFSA standards.
• Oxidation assay (direct TOP assay) to identify PFAS precursors.

Main Results:

• Identification of 10 new PFAS classes and 73 individual PFAS, including novel compounds.
• Over 75% of the total PFAS concentration was attributed to newly identified substances (>30 μg/g).
• Pentafluorosulfanyl (SF5) PFSAs were the dominant class (~40%).
• The direct TOP assay identified precursors but covered less than 23% of the total PFAS, underscoring NTS importance.

Conclusions:

• Nontarget screening is crucial for a comprehensive characterization of complex PFAS soil contamination.
• A significant portion of PFAS in the studied soil consists of previously unidentified and potentially non-degradable compounds.
• Advanced analytical techniques are necessary to fully understand the extent and nature of PFAS pollution.